In Redis, the ZSCORE
command returns the score of the specified member of a sorted set.
Syntax
The syntax goes like this:
ZSCORE key member
Example
Suppose we create a sorted set like this:
ZADD cats 15 Meow 27 Fluffy 43 Scratch 84 Purr 25 Bite 37 Bunting
Result:
(integer) 6
In my case the sorted set didn’t exist, and so it was created and the six elements were added as specified.
Let’s now use the ZSCORE
command to find out the score of a given member:
ZSCORE cats Scratch
Result:
"43"
The member has a score of 43
as expected.
Let’s try another member:
ZSCORE cats Meow
Result:
"15"
As expected.
When the Member or Key Doesn’t Exist
If the member doesn’t exist we get nil
:
ZSCORE cats Fur
Result:
(nil)
Same when the key doesn’t exist:
ZSCORE dogs Meow
Result:
(nil)
We can use the EXISTS
command to check for the existence of a key:
EXISTS dogs
Result:
(integer) 0
An integer reply of zero means that it doesn’t exist.
Wrong Type
If the key contains the wrong data type, an error occurs:
ZSCORE animals Bite
Result:
(error) WRONGTYPE Operation against a key holding the wrong kind of value
In my case, the animals
key contains a set (not a sorted set) and so we get the error.
We can use the TYPE
command to check the key’s data type:
TYPE animals
Result:
set
As suspected, it’s a set.